Dependence of the Characteristics of Wood Charcoal on the Carbonization Conditions

김대영,권구중,강주현 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.67 No.4

We examined the characteristics of wood charcoal generated from ubame oak (Quercus phillyraeoides) and sugi (Cryptomeria japonica) at different carbonization temperatures up to 1200 C with different heating rates of 0.1, 1 and 10 C/min. In general, pyrolysis was achieved at a lower temperature when a lower heating rate was applied for both of the wood species. At temperatures greater than or equal to 400 C, Sugi showed a relatively smaller weight loss at a heating rate of 1 C/min compared to the other hearing rates while the amount of the weight loss changed little regardless of the heating rate for ubame oak. At 600 C, a lower heating rate resulted in a greater char yield for sugi while a heating rate of 1 C/min produced the greatest char yield for ubame oak. At this temperature condition, the largest specific surface areas obtained were 827 m2/g at 10 C/min and 447.9 m2/g at 1 C/min for sugi and ubame oak, respectively. At 1200 C, the greatest char yield was obtained at a heating rate of 1 C/min for both wood species, and a lower heating rate produced a greater specific surface area for sugi while a porous structure was rarely observed in ubame oak. The X-ray diffractograms of the charcoals of the two wood species showed the noncrystalline structure of graphite carbon for all the tested hearing rates. The bending strength of the charcoal was the greatest at heating rates of 1 C/min and 0.1 C/min for sugi and ubame oak, respectively. Furthermore, a higher temperature provided a greater compressive strength of the charcoals. The modulus of elasticity changed little with changing carbonization temperature or changing heating rate.

Reactive force-field simulation of the effect of heating rate on pyrolysis behavior of lignite

Fang Xu,Qing Wang,Chengchang Wu 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.3

With the help of ReaxFF-MD simulations, the non-isothermal pyrolysis behavior of lignite, especially the effect of heating rate on pyrolysis products, has been investigated in detail. The results demonstrate that increasing the heating rate is very helpful for the production of tar at lower heating rates. By contrast, at relatively high heating rates, further increasing the heating rate has less effect on the distribution of pyrolysis products. Moreover, the evolution tendencies of char and tar at lower heating rates are different from those at the relatively higher heating rates, which exist as remarkable turning points in the high temperature region. This is probably because the reaction time is longer at lower heating rates, and the possibilities of condensation and further decomposition of tar are much greater at high temperatures. Additionally, the relationship between system energy and reaction mechanism was revealed. The results indicate that with the same reaction mechanism, the system energies of non-isothermal pyrolysis are approximately equal and hardly affected by the heating rate. Finally, taking 2 K/ps as an example, the secondary reaction mechanism of tar was further analyzed, and some possible secondary reaction pathways were proposed.

방전플라즈마소결법 적용 승온속도 변화에 따라 제조된 Fe-20Cu-1C 소결체 제조 및 특성평가

유정한,신수식,유병록,김경식,장준호,오익현,김갑태,박현국,Ryu, Jung-Han,Shin, Soo-Sik,Ryu, Byung-Rok,Kim, Kyung-Sik,Jang, Jun-Ho,Oh, Ik-Hyun,Kim, Kap-Tae,Park, Hyun-Kuk 한국분말야금학회 2017 한국분말재료학회지 (KPMI) Vol.24 No.4

In this study, Fe-Cu-C alloy is sintered by spark plasma sintering (SPS). The sintering conditions are 60 MPa pressure with heating rates of 30, 60 and $9^{\circ}C/min$ to determine the influence of heating rate on the mechanical and microstructure properties of the sintered alloys. The microstructure and mechanical properties of the sintered Fe-Cu-C alloy is investigated by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). The temperature of shrinkage displacement is changed at $450^{\circ}C$ with heating rates 30, 60, and $90^{\circ}C/min$. The temperature of the shrinkage displacement is finished at $650^{\circ}C$ when heating rate $30^{\circ}C/min$, at $700^{\circ}C$ when heating rate $60^{\circ}C/min$ and at $800^{\circ}C$ when heating rate $90^{\circ}C/min$. For the sintered alloy at heating rates of 30, 60, and $90^{\circ}C/min$, the apparent porosity is calculated to be 3.7%, 5.2%, and 7.7%, respectively. The hardness of the sintered alloys is investigated using Rockwell hardness measurements. The objective of this study is to investigate the densification behavior, porosity, and mechanical properties of the sintered Fe-Cu-C alloys depending on the heating rate.

Influence of Temperature and Humidity on Pregnancy Rate of Murrah Buffaloes under Subtropical Climate

Soumya Dash,A. K. Chakravarty,V. Sah,V. Jamuna,R. Behera,N. Kashyap,B. Deshmukh 아세아·태평양축산학회 2015 Animal Bioscience Vol.28 No.7

Heat stress has adverse effects on fertility of dairy animals. Decline in fertility is linearly associated with an increase in combination of both temperature and humidity. The purpose of this study was to investigate the relationship between temperature humidity index (THI) and the pregnancy rate of Murrah buffaloes in a subtropical climate. The effects of genetic and non-genetic factors viz., sire, parity, period of calving and age group at first calving were found non-significant on pregnancy rate. The effect of THI was found significant (p<0.001) on pregnancy rate of Murrah buffaloes calved for first time and overall pregnancy rate. The threshold THI affecting the pregnancy rate was identified as THI 75. The months from October to March showed THI<75 and considered as non heat stress zone (NHSZ), while months from April to September were determined as heat stress zone (HSZ) with THI≥75. The lowest overall pregnancy rate (0.25) was obtained in July with THI 80.9, while the highest overall pregnancy rate (0.59) was found in November with THI 66.1. May and June were identified as critical heat stress zone (CHSZ) within the HSZ with maximum decline (−7%) in pregnancy rate with per unit increase in THI. The highest overall pregnancy rate was estimated as 0.45 in NHSZ with THI value 56.7 to 73.2. The pregnancy rate was found to have declined to 0.28 in HSZ with THI 73.5 to 83.7. However, the lowest pregnancy rate was estimated as 0.27 in CHSZ with THI value 80.3 to 81.6.

Influence of Temperature and Humidity on Pregnancy Rate of Murrah Buffaloes under Subtropical Climate

Dash, Soumya,Chakravarty, A.K.,Sah, V.,Jamuna, V.,Behera, R.,Kashyap, N.,Deshmukh, B. Asian Australasian Association of Animal Productio 2015 Animal Bioscience Vol.28 No.7

Heat stress has adverse effects on fertility of dairy animals. Decline in fertility is linearly associated with an increase in combination of both temperature and humidity. The purpose of this study was to investigate the relationship between temperature humidity index (THI) and the pregnancy rate of Murrah buffaloes in a subtropical climate. The effects of genetic and non-genetic factors viz., sire, parity, period of calving and age group at first calving were found non-significant on pregnancy rate. The effect of THI was found significant (p<0.001) on pregnancy rate of Murrah buffaloes calved for first time and overall pregnancy rate. The threshold THI affecting the pregnancy rate was identified as THI 75. The months from October to March showed THI<75 and considered as non heat stress zone (NHSZ), while months from April to September were determined as heat stress zone (HSZ) with $THI{\geq}75$. The lowest overall pregnancy rate (0.25) was obtained in July with THI 80.9, while the highest overall pregnancy rate (0.59) was found in November with THI 66.1. May and June were identified as critical heat stress zone (CHSZ) within the HSZ with maximum decline (-7%) in pregnancy rate with per unit increase in THI. The highest overall pregnancy rate was estimated as 0.45 in NHSZ with THI value 56.7 to 73.2. The pregnancy rate was found to have declined to 0.28 in HSZ with THI 73.5 to 83.7. However, the lowest pregnancy rate was estimated as 0.27 in CHSZ with THI value 80.3 to 81.6.

중앙집중난방방식 공동주택의 난방열량 계량 및 요금부과방안 연구

이태원(Tae-Won Lee),김용기(Yong-Ki Kim) 대한설비공학회 2009 대한설비공학회 학술발표대회논문집 Vol.2009 No.-

The measuring apparatus such as heat meter is legally obliged to be installed and used for heat rating with heat or flow rate in residential buildings in Korea. There are two kinds of apparatus to measure heat consumed at each households, i.e., heat meter and hot water flowmeter. Contrast to the most of buildings with hot water flowmeter well being used for rating, heat meters have been used only 42.6% in the buildings with central heating system. But there is a critical problem in the course of using hot water flowmeter for heat rating, yielding distorted and unfair result which is different from the real value of heat supplied. Experiments with several parameters were carried out in this study to analyze this phenomenon quantively and alternative methods were proposed for rational heat rating.

Conduction Heating of Boron Alloyed Steel in Application for Hot Stamping

Weikang Liang,Yong Liu,Bin Zhu,Minglin Zhou,Yisheng Zhang 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.

In traditional hot stamping process, heating of the sheet by radiation heating occupies most of cycle time, which limits the application of hot stamping in automotive industry. Thus a faster heating method has great significance on the hot stamping. The conduction heating overcomes shortage of the radiation heating because of higher heating rate and greater energy efficiency. It attracts increasing attention in the application of heating blanks in hot stamping. In the present study, a movable conduction heating device on die was designed in terms of the Joule’s Law. Heating experiments of boron alloyed steel were performed using the developed device. Heating rate and uniform temperature region were investigated in the non-heat preservation condition (NHPC) and the heat preservation condition (HPC). The results revealed that in the HPC, the heating rate was improved by 13.1 °C/s. In addition, the length of the uniform temperature region was lengthened by 15 mm. It was demonstrated that the HPC was preferred. Furthermore, it was indicated that the mechanical properties of the blanks in uniform temperature region of the conduction heating were also superior to that of the radiation heating.

Fracture toughness of high performance concrete subjected to elevated temperatures Part 2 The effects of heating rate, exposure time and cooling rate

Zhang, Binsheng,Cullen, Martin,Kilpatrick, Tony Techno-Press 2017 Advances in concrete construction Vol.5 No.5

In this study, the fracture toughness $K_{IC}$ of high performance concrete (HPC) was investigated by conducting three-point bending tests on a total of 240 notched beams of $500mm{\times}100mm{\times}100mm$ subjected to heating temperatures up to $450^{\circ}C$ with exposure times up to 16 hours and various heating and cooling rates. For a heating rate of $3^{\circ}C/min$, $K_{IC}$ for the hot concrete sustained a monotonic decrease trend with the increasing heating temperature and exposure time, from $1.389MN/m^{1.5}$ at room temperature to $0.942MN/m^{1.5}$ at $450^{\circ}C$ for 4-hour exposure time, $0.906MN/m^{1.5}$ for 8-hour exposure time and $0.866MN/m^{1.5}$ for 16-hour exposure time. For the cold concrete, $K_{IC}$ sustained a two-stage decrease trend, dropping slowly with the heating temperature up to $150^{\circ}C$ and then rapidly down to $0.869MN/m^{1.5}$ at $450^{\circ}C$ for 4-hour exposure time, $0.812MN/m^{1.5}$ for 8-hour exposure time and $0.771MN/m^{1.5}$ for 16-hour exposure time. In general, the $K_{IC}$ values for the hot concrete up to $200^{\circ}C$ were larger than those for the cold concrete, and an inverse trend was observed thereafter. The increase in heating rate slightly decreased $K_{IC}$, and at $450^{\circ}C$ $K_{IC}$ decreased from $0.893MN/m^{1.5}$ for $1^{\circ}C/min$ to $0.839MN/m^{1.5}$ for $10^{\circ}C/min$ for the hot concrete and from $0.792MN/m^{1.5}$ for $1^{\circ}C/min$ to $0.743MN/m^{1.5}$ for $10^{\circ}C/min$ for the cold concrete after an exposure time of 16 hours. The increase in cooling rate also slightly decreased $K_{IC}$, and at $450^{\circ}C$ $K_{IC}$ decreased from $0.771MN/m^{1.5}$ for slow cooling to $0.739MN/m^{1.5}$ for fast cooling after an exposure time of 16 hours. The fracture energy-based fracture toughness $K_{IC}$' was also assessed, and similar decrease trends with the heating temperature and exposure time existed for both hot and cold concretes. The relationships of two fracture toughness parameters with the weight loss and the modulus of rapture were also evaluated.

An Experimental Verification Study on the Heat Flow Analysis Results of a Tube Furnace

Byungsuk Park,Sangwoon Kwon,Juho Lee,Changhwa Lee 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.2

In general, systems are developed by repeatedly performing the processes of design, analysis, manufacturing, and performance testing. In particular, systems with temperature, pressure, and flow rate often utilize computational fluid dynamics tools at the design stage. In this paper, we aim to verify the reliability of the analysis results of Solidworks Flow Simulation, which is widely used in heat flow analysis at the design stage. A tube furnace was manufactured, various experiments were performed, and a study was conducted to compare the analysis results. The details of the experiment are as follows. First, an experiment was conducted in which the heater was heated to 900°C without insulating the exposed part of the tube. The detailed contents of the experiment are as follows; - Heating heater and measuring temperature without supplying flow inside the tube, - Tube flow supply (25°C, 15 lpm air) and heater heating/temperature measurement. Second, an experiment was performed in which the exposed part of the tube was insulated (thickness 50 mm) and the heater was heated to 900°C. The detailed contents of the experiment are as follows; - Insulate the outside of the tube except for the flanges at both ends of the tube, and heat the heater and measure the temperature without supplying flow inside the tube. - Insulate the outside of the tube except for the flanges at both ends of the tube, supply flow rate inside the tube (25°C, 15 lpm air) and measure heater heating/temperature. - Insulate the flange of the flow supply section, heat the heater and measure temperature without supplying flow inside the tube. - Insulate the flange of the flow supply section, heat the supply air (277°C, 15 lpm) and measure the temperature using a heating gun without heating the heater. - Insulate the flange of the flow supply section, supply heated air (277°C, 15 lpm) and measure heater heating/temperature. - Insulate the flange of the flow supply section and measure temperature according to heater heating (900°C) and supply temperature (25°C, 277°C 15 lpm). The following results were derived from the experimental and analysis results. - When the exposed part of the tube is insulated, the temperature inside the tube increases and the steady-state power decreases compared to non-insulated. - In areas with insulation, the temperature error between experiment and analysis results is not large. - When flow rate is supplied, there is a large temperature error in experiment and analysis results. - The temperature change after the center of the heater is not large for a temperature change of 15 lpm flow rate. From these results, it can be seen that Solidworks Flow Simulation has a significant difference from the experimental results when there is a flow rate in the tube. This was thought to be because the flow rate acts as a disturbance, and this cannot be sufficiently accounted for in the analysis. In the future, we plan to check whether there is a way to solve this problem.

Heat transfer and flow characteristics of a cooling thimble in a molten salt reactor residual heat removal system

Zonghao Yang,Zhaoming Meng,Changqi Yan,Kailun Chen 한국원자력학회 2017 Nuclear Engineering and Technology Vol.49 No.8

In the passive residual heat removal system of a molten salt reactor, one of the residual heat removalmethods is to use the thimble-type heat transfer elements of the drain salt tank to remove the residualheat of fuel salts. An experimental loop is designed and built with a single heat transfer element toanalyze the heat transfer and flow characteristics. In this research, the influence of the size of a threelayerthimble-type heat transfer element on the heat transfer rate is analyzed. Two methods are usedto obtain the heat transfer rate, and a difference of results between methods is approximately 5%. The gasgap width between the thimble and the bayonet has a large effect on the heat transfer rate. As the gasgap width increases from 1.0 mm to 11.0 mm, the heat transfer rate decreases from 5.2 kW to 1.6 kW. Inaddition, a natural circulation startup process is described in this paper. Finally, flashing natural circulationinstability has been observed in this thimble-type heat transfer element.